Primer: cytopathology for the clinician--how to interpret the results of aspiration cytology.

The practice of clinical cytopathology is characterized by the daily challenges of trying to establish pathological diagnoses on the basis of microscopic evaluation of small cellular samples, from both deep-seated and superficial anatomic sites. The diagnostic work-up of mass lesions involves a collaborative effort between clinicians and pathologists, and relies on the pathologist's ability to establish a reliable diagnosis; that is, one that convincingly explains the mass and its underlying neoplastic or non-neoplastic nature. Arriving at a conclusive pathological diagnosis is not always easy and additional ancillary tests, such as special stains, microbiologic cultures and flow cytometry, are often required. To ensure that clinicians can make appropriate management decisions, it is essential that pathologists use conventionally accepted diagnostic nomenclature and communicate effectively with their clinical colleagues. Clinicians should also ensure that the pathologist is provided with all relevant clinical information, preferably at the time of submission of the specimen. Clinicians should consult with the pathologist before the biopsy procedure, and inform them of the clinical differential diagnoses, to ensure that the proper ancillary tests are obtained for definite diagnosis.